An automatic analyzer of a type, which uses a rack sampler, has been developed. The automatic analyzer of this type is equipped with, for example, a convey mechanism and pull-in mechanism. The convey mechanism conveys a rack which stores cuvettes containing samples to be measured using a belt conveyor and the like to a pull-in position. The pull-in mechanism pulls in the rack from the pull-in position to a sample suction position.
When the rack is not accurately placed at a placement position on the convey mechanism, the rack may fall or the position of a cuvette of a sample to be measured may deviate from the sample suction position.
The following methods for detecting whether or not the rack is normally placed on the convey mechanism are adopted.
1. A movable portion, which moves by the self weight of the rack, is set on the convey mechanism. The movement of the movable portion is detected by a sensor. A mechanism in which the movement of the movable portion changes depending on whether or not the rack is placed at an accurate position is provided. By detecting the movement of the movable portion, whether or not the rack is placed at an accurate placement position is detected. In this case, it is difficult to balance between the self weight of the rack and a change in movement of the movable portion. Since the rack is moved by the movable portion, the rack readily falls. In order to avoid falling, the size of the rack has to be increased, thus disturbing a size reduction of the rack and apparatus.
2. A sensor for detecting the rack is set on the pull-in mechanism of the rack. This sensor is used to confirm whether or not the track is accurately pulled in and whether or not the rack is accurately placed at the pull-in position. In this manner, whether or not the rack is placed at a rack placement position of the convey mechanism can be confirmed. However, in this case, whether or not the rack is accurately placed at the rack placement position on the convey mechanism cannot be confirmed before the rack is conveyed to the pull-in position.
An object of the embodiment is to provide an automatic analyzer which can safely convey a rack after the rack is placed at an accurate position on a convey mechanism.